.TH YAWS.CONF "5" "" "" "User Commands"
.SH NAME
/etc/yaws.conf \- Configuration file for the yaws webserver
.SH DESCRIPTION
.\" Add any additional description here
.PP
Yaws is fast lightweight webserver. It reads a configuration file called
yaws.conf to control its operations. The configuration contains two distinct
parts a global part which affects all the virtual hosts and a server part
where options for each virtual host is supplied.

.SH GLOBAL PART
.TP

\fBlogdir = Directory\fR
All yaws logs will be written to files in this directory. There are several
different log files written by yaws.

.br
\fBreport.log\fR - this is a text file that contains all error logger 
printouts from yaws. 

.br
\fBHost.access\fR - for each virtual host served by yaws, a file Host.access
will be written which contains an access log in Common Log Format.

.br
\fBtrace.http\fR - this file contains the HTTP trace if that is enabled

.br 
\fBauth.log\fR - If configured, all http auth related messages
goes here.

.br
\fBtrace.traffic\fR - this file contains the traffic trace if that is enabled

The default value for logdir is "."

.TP
\fB ebin_dir = Directory\fR
This directive adds Directory to the erlang search path. It is possible to
have several of these command in the configuration file.


.TP
\fB id = String\fR
It is possible run multiple yaws servers on the same machine. We use the
id of a yaws server to control it using the different ctl commands such
as:
.nf

# /usr/local/bin/yaws --id foobar --stop

.fi
To stop the Yaws server with id "foobar". Each Yaws server will write
its internals data into a file called $HOME/.yaws/yaws/ID where ID the
identity of the server. Yaws also creates a file called
${VARDIR}/run/yaws/ctl-${ID} which contain the portnumber where the server is
listening for control commands.

.TP
\fB include_dir = Directory\fR
This directive adds Directory to the path of directories where the erlang
compiler seraches for include files. We need to use this if we want to 
include .hrl files in our yaws erlang code.
.TP
\fB max_num_cached_files = Integer\fR
Yaws will cache small files such as commonly accessed GIF images in RAM.
This directive sets a maximum number on the number of cached files.
The default value is 400.
.TP 
\fB max_num_cached_bytes = Integer\fR
This directive controls the total amount of RAM which can maximally be
used for cached RAM files. The default value is 1000000, 1 megabyte.
.TP
\fB max_size_cached_file = Integer\fR
This directive sets a maximum size on the files that are RAM cached by yaws.
The default value i 8000, 8 kBytes.
.TP
\fB cache_refresh_secs = Integer\fR
The RAM cache is used to serve pages that sit in the cache. An entry sits in
cache at most cache_refresh_secs number of seconds. The default is 30. This means that when the content is updated under the docroot, that change doesn't show
until 30 seconds have passed. While developing a yaws site, 
it may be convenient to set this value to 0. If the debug flag (-d) is passed
to the yaws start script, this value is automatically set to 0.

.TP
\fB trace  = traffic | http\fR
This enables traffic or http tracing. Tracing is also possible to enable with
a command line flag to yaws.


.TP
\fB auth_log  = true | false\fR
Enable or disable the auth log. Default is true.

.TP
\fB log_wrap_size = Integer\fR
The logs written by yaws are all wrap logs, the default value at the
size where they wrap around and the original gets renamed to File.old
is 1000000, 1 M. This value can changed.

.TP
\fB tmpdir = Dir\fR
Yaws generates files when generating dynamic content, i.e. when
processing .yaws pages. These files end up in tmpdir. Default
is $HOME/.yaws


.TP
\fB log_resolve_hostname = Bool\fR
By default the client host IP is not resolved in the access logs.


.TP
\fB fail_on_bind_err = Bool\fR
Fail completely or not if yaws fails to bind a listen socket
Default is true.

.TP
\fB enable_soap = Bool\fR
If true, a soap server will be started at startup of Yaws.
Default is false.


.TP
\fBphp_exe_path = Path\fR
The name of (and possibly path to) the php executable used to
interpret php scripts (if allowed).  Default is 
\fIphp_exe_path = php-cgi\fR.

.TP
\fB copy_error_log  = true | false\fR
Enable or disable copying of the error log. When we run in
embedded mode, there may very well be some other systems process
that is responsible for writing the errorlog to a file whereas
when we run in normal standalone mode, we typically want the
erlang errorlog written to a report.log file.
Default value is true.


.TP
\fBbackwards_compat_parse  = true | false\fR
Versions of Yaws > than 1.41 changes the return value
of the parse_query and parse_post functions. Earlier versions
used {Key, Val} where Key was an atom. This made Yaws vulnerable
for DOS attacks. Set this flag to keep the old deprecated 
and vulnerable behaviour. In versions >  1.41 the Key is a list/string.


.TP
\fB username = Username \fR
When running a Yaws server in production, it may feel safe
to run yaws as a different user than root. Set this value to a 
non priviliged username on the system, such as "nobody".
Yaws will initially have to run a root in order to properly
listen to priviliged ports .


.TP
\fB pick_first_virthost_on_nomatch = true | false \fR
When Yaws gets a request, it extracts the Host: header from the
client request to choose a virtual server amongst all servers
with the same IP/Port pair.
This configuration parameter decides wether yaws should pick the
first (as difined in the yaws.conf file) if no name match or not.
In real live hosting scenarios we typically want this to be false
whereas in testing/development scenarios we want 

.TP
\fB use_fdsrv = true | false \fR
This feature makes it possible to bind to ports < 1024 even when
we're not running as root. It requires the Jungerl package called fd_server
to be properly installed.. The feature doen't (yet) work with SSL.

.TP
\fB use_large_ssl_pool = true | false \fR
SSL servers by default has a pool of pending accept processes.

An SSL connection might include user interaction.
So while one person has a dialog box on the screen asking him to review
the server's certificate, no other person is able to establish a new
connnection to the server unless we run multiple SSL acceptor processes.
The default is 8, if we set the this configurable, we use 50 pending
accept processes. So in environments where a large number of slow
connectors is expected, this configurable makes sense.

.TP
\fB subconfig = File \fR
Load specified config file.

.TP
\fB subconfigdir = Directory \fR
Load all config file in specified directory.


.SH SERVER PART
Yaws can virthost several webservers on the same ip address as well
as several webservers on different ip addresses. The on limitation here is
that there can be only one server with ssl enabled per each individual ip address.
.pp
Each virttual host is defined within a matching pair of \fB<server ServerName>\fR
and \fB</server>\fR. The ServerName will be the name of the webserver.

.pp
The following directives are allowed inside a server definition.
.TP
\fBport = Port \fR
This makes the server listen on Port
.TP
\fBlisten = IpAddress\fR
This makes the server listen on IpAddress
When virthosting several servers on the same ip/port address, if the
browser doesn't send a Host: field, yaws will pick the \fIfirst\fR
server specified in the config file.
If the specified ip address is 0.0.0.0 yaws will listen on all local ip
addresses on the specified port.

.TP
\fBrhost = Host[:Port] \fR
This forces all local redirects issued by the server to go to Host.
This is useful when yaws listens to a port which is different from 
the port that the user connects to. For example, running yaws as a
non-privileged user makes it impossible to listen to port 80, since
that port can only be opened by a privileged user. Instead yaws
listens to a high port number port, 8000, and iptables are used to 
redirect traffic to port 80 to port 8000 (most NAT:ing firewalls 
will also do this for you).
.TP
\fBrscheme = http | https \fR
This forces all local redirects issued by the server to use this 
method. This is useful when an SSL off-loader, or stunnel, is used in 
front of yaws.
.TP


\fBaccess_log = true | false\fR
Setting this directive to false turns of traffic logging for this
virtual server. The default value is true. 

.TP
\fBdir_listings = true | true_nozip | false\fR
Setting this directive to false disallows the automatic
dir listing feature of Yaws. A status code 403 Forbidden will be sent.
Set to true_nozip to avoid the auto-generated all.zip entries.

.TP
\fBdeflate = true | false\fR
Turns on or off deflate compression for a server

.TP
\fB docroot = Directory ...\fR
This makes the server serve all its content from Directory.

It is possible to pass a space separated list of directories as 
docroot. If this is the case, the various directories will be searched in
order for the requested file. This also works with the ssi
and yssi constructs where the full list of directories will be searched
for files to ssi/yssi include.


.TP
\fBpartial_post_size = Integer\fR
When a yaws file receives large POSTs, the amount of data received
in each chunk is determined by the this parameter.
The deafult value is 10240.

.TP
\fB dav = true | false\fR
Turns on the DAV protocol for this server.

.TP
\fBtilde_expand = true|false \fR
If this value is set to false yaws will never
do tilde expansion. The default is false. tilde_expansion is the
mechanism whereby a URL ob the form http://www.foo.com/~username
is changed into a request where the docroot for that
particular request is set to the directory ~username/public_html/
The default value is false.

.TP
\fBallowed_scripts = [ListOfSuffixes]\fR
The allowed script types for this server.  Recognized are `yaws',
`cgi', `php'.  Default is \fIallowed_scripts = yaws\fR.

.TP
\fBappmods = [ListOfModuleNames]\fR
If any the names in ListOfModuleNames appear as components in the
path for a request, the path request parsing will terminate and
that module will be called. There is also an alternate syntax for
specifying the appmods if we don't want our internal erlang module
names to be exposed in the URL paths. 
We can specify

   appmods = <Path1, Module1> <Path2, Modules2> ...

Assume for example that we have
the URL http://www.hyber.org/myapp/foo/bar/baz?user=joe 
while we have the module foo defined as an appmod, the 
function foo:out(Arg) will be invoked
instead of searching the filesystems below the point foo.

The Arg argument will have the missing path part supplied in its
appmoddata field. 


.TP
\fBerrormod_404 = Module\fR
It is possible to set a special module that handles
404 Not Found messages.

The function \fIModule:out404(Arg, GC, SC)\fR will
be invoked. The arguments are

Arg is a #arg{} record

GC is a #gconf{} record (defined in yaws.hrl)

SC is a #sconf{} record (defined in yaws.hrl)

The function can and must do the same things that 
a normal \fIout/1\fR does.


.TP
\fBerrormod_crash = Module\fR
It is possible to set a special module that handles
the HTML generation of server crash messages. The default
is to display the entire formated crash message in the
browser. This is good for debugging but not in production.

The function \fIModule:crashmsg(Arg, SC, Str)\fR will be
called. The \fIStr\fR is the real crash message formated as a string.


.TP
\fBarg_rewrite_mod = Module\fR
It is possible to install a module that rewrites all the 
Arg #arg{} records at an early stage in the yaws server.
This can be used to do various things such as checking a cookie,
rewriting paths etc.

.TP
\fBstart_mod = Module\fR
Defines a user provided callback module.
At startup of the server, Module:start/1 will be called.
The #sconf{} record (defined in yaws.hrl) will be used
as the input argument. This makes it possible for a user
application to syncronize the startup with the yaws server
as well as getting hold of user specific configuration data,
see the explanation for the <opaque> context.



.TP
\fBrevproxy = Prefix Url\fR
Make yaws a reverse proxy. The Prefix is a path inside our own docroot
and the Url argument is an url pointing to a website we want to "mount"
under the path which is Prefix.

Example: revproxy = /tmp/foo http://yaws.hyber.org

Makes the hyber website appear under /tmp/foo

It is possible to have multiple reverse proxies inside the same server.

WARNING, this feature is yet not in production quality.


.TP
\fBservername = Name\fR
If we're virthosting everal servers and want to force a server
to match specific Host: headers we can do this with the "servername"
directive. This name doesn't necessarily have to be the same as the
the name inside <server Name> in certain NAT scenarios. Rarely used feature.


.TP
\fB <ssl>  .... </ssl> \fR
This begins and ends an SSL configuration for this server.
.TP
\fB keyfile = File\fR
Specifies which file contains the private key for the certificate.
.TP
\fB certfile = File\fR
Specifies which file contains the certificate for the server.
.TP
\fB cacertfile = File\fR
File If the server is setup to require client certificates. This file needs to contain all the certificates of the acceptable signers for the client certs.
.TP
\fB verify = 1 | 2 | 3\fR
Specifies the level of verification the server does on clinet certs. 1 means nothing, 2 means the the server will ask the client for a cert but not fail if the client doesn't supply a client cert, 3 means that the server requires the client to supply a client cert.
.TP
\fB depth = Int\fR
Specifies the depth of certificate chains the server is prepared to follow when verifying client certs.
.TP
\fB password = String\fR
String If the private key is encrypted on disc, this password is the 3des key to decrypt it.

.TP
\fB ciphers = String\fR
* This string specifies the ssl cipher string. The syntax of the ssl cipher string is a little horrible sublanguage of its own. It is documented in the ssl man page for "ciphers". 

.TP
\fB </ssl> \fR
Ends an SSL definition

 
.TP
\fB<redirect> ... </redirect>\fR
Defines an redirect mapping. The following items are allowed
within a matching pair of <redirect> and </redirect> delimiters.

.TP
\fBPath = [Scheme://]Host[:Port]\fR
All accesses to Path will be redirected to [Scheme://]Host[:Port]Path.
Scheme and Port is optional. The default is to use the servers scheme
and port, rsheme and rport will be used if defined. To redirect
all references to a site use "/" as Path.

.TP
\fB<auth> ... </auth>\fR
Defines an auth structure. The following items are allowed
within a matching pair of <auth> and </auth> delimiters.

.TP
\fBdir = Dir\fR
Makes Dir to be controlled bu WWW-authenticate headers. In order for
a user to have access to WWW-Authenticate controled directory, the user
must supply a password. The Dir must be specified relative to the docroot.

.TP
\fBrealm = Realm\fR
In the directory defined here, the WWW-Authenticate Realm is set to
this value. 

.TP
\fBauthmod = AuthMod\fR
If an auth module is defined then AuthMod:auth(Arg, Auth) will
be called for all access to the directory. The auth/2 function 
should return one of: true, false, {false, realm}, {appmod, Mod}.
If {appmod, Mod} is returned then a call to Mod:out(Arg) will
be used to deliver the content.

This can, for example, be used to implement cookie authentication.
The auth() callback would check if a valid cookie header is present,
if not it would return {appmod, ?MODULE} and the out/1 function 
in the same module would return {redirect_local, "/login.html"}.

.TP
\fBuser = User:Password\fR
Inside this directory, the user User has access if the user supplies
the password Password in the popup dialogue presented by the browser.
We can obviously have several of these value inside a single <auth> </auth>
pair.

The usage of User:Password in the actual config file is deprecated
as of release 1.51. It is prefered to have the users in a file called
\fI.yaws_auth\fR in the actual directory. The .yaws_auth file has to be
file parseable by \fIfile:consult/1\fR

Each row of the file must contain terms on the form

.nf
{User, Password}.
.fi

Where both User and Password should be strings.
The .yaws_auth file mechanism is not (yet) recursive. Thus
any subdirectories to Dir are not automatically also protected.

The .yaws_auth file is never visible in a dir listing

.TP
\fBpam service = \fIpam-service\fR \fR
If the item \fBpam\fR is part of the auth structure, 
Yaws will also try to authenticate the user using "pam" using
the pam \fIservice\fR indicated. Usual services are typically found
under /etc/pam.d. Usual values are "system-auth" etc.

pam authentication is performed by an Erlang port program which is
typically installed as suid root by the yaws install script.

.TP
\fB</auth>\fR
Ends an auth definition

.TP
\fB <opaque>  .... </opaque> \fR
This begins and ends an opaque configuration context for this server,
where 'Key = Value' directives can be specified. These directives are
ignored by yaws (hence the name opaque), but can be accessed as a list
of tuples \fI{Key,Value}\fR stored in the #sconf.opaque record entry. See also
the description of the \fIstart_mod\fR directive. 

This mechanism can be used to pass data from a surrounding application
into the individual .yaws pages.

.TP
\fB keyfile = File\fR


.SH EXAMPLES

The following example defines a single server on port 80.
.nf

logdir = /var/log/yaws
<server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
</server>
.fi

.pp
And this example shows a similar setup but two webservers on the same ip address

.nf

logdir = /var/log/yaws
<server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
</server>

<server www.funky.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www_funky_org
</server>


.fi


.nf
An example with www-authenticate and no access logging at all.

logdir = /var/log/yaws
<server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
        access_log = false
        <auth>
            dir = secret/dir1
            realm = foobar
            user = jonny:verysecretpwd
            user = benny:thequestion
            user = ronny:havinganamethatendswithy
       </auth>

</server>





.fi

.nf
An example specifying  a user defined module to be called
at startup, as well as some user specific configuration.
 
<server www.funky.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www_funky_org
	start_mod = btt
	<opaque>
		mydbdir = /tmp
		mylogdir = /tmp/log
	</opaque>
</server>


.fi



And finally a sligthly more complex example
with two servers on the same ip, and one ssl server on a
different ip.

When there are more than one server on the same IP, and they have different
names the server must be able to choose one of them if the client
doesn't send a Host: header. yaws will choose the first one defined in the
conf file.

.nf

logdir = /var/log/yaws
max_num_cached_files = 8000
max_num_cached_bytes = 6000000

<server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
</server>



<server www.funky.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www_funky_org
</server>

<server www.funky.org>
        port = 443
        listen = 192.168.128.32
        docroot = /var/yaws/www_funky_org
        <ssl>
           keyfile = /etc/funky.key
           certfile = /etc/funky.cert
           password = gazonk
        </ssl>
</server>


.fi

.SH AUTHOR
Written by Claes Wikstrom
.SH "SEE ALSO"
.BR yaws (1)
.BR erl (1)

